Breathers are used to release air pressure, which builds up during operation, from within a housing for driveline components such as axles, transfer cases, and transmissions. One problem with current breathers is that the breathers provide a leakage path for lubricating fluid contained within the housing. This leaking can be generated by several different operational modes, such as pumping, splashing, and spattering caused by internal driveline components enclosed within the housing. Air flow rate, fluid temperature, changes in operational speed, etc. can also affect leakage amounts.
Several different solutions have been proposed to address this problem but have had limited success. One solution provides a breather body that is threaded into the housing with one end extending outwardly from the housing and an opposite end being flush with an internal wall of the housing. The breather body has an internal bore that includes a pair of baffles offset from each other to block lubricating fluid from exiting the bore. During operation a thick film of fluid bridges an opening to the internal bore at the internal wall of the housing. This thick film of fluid causes fluid to collect at the breather location, which is undesirable. The baffles prevent some but not all of the lubricating fluid from exiting the breather.
Mesh screens have also been used in place of baffles to prevent fluid from exiting the breather. These mesh screens have a tendency to clog and do not allow fluid to drain back into the housing.
Another solution provides a breather body with a tube that extends into the housing cavity. The tube has the same problems identified above. A thick film of fluid bridges an opening at an internal end of the tube, which results in fluid being drawn to the breather. Further, the tube does not prevent fluid that is splashed or splattered in a direction toward the tube from exiting the breather.
Thus, there is a need for a breather that can prevent lubricating fluid from exiting the breather under harsh operating conditions while still allowing air to vent as needed.